Calculate the change in intensity level when the intensity of sound increase by 106 times the original intensity *
Answers
Answer:
The physiological sensation of loudness is related to the intensity of the wave producing the sound. At a frequency of 1 kHz, people are able to detect sound with intensity as low as 10^-12 watt per metre squared.
On the other hand an intensity of 1 watt per square metre can cause pain, and a prolonged exposure at this sound level could damage hearing.
The range in intensity over which people hear sound is so large, that it is convenient to use a logarithmic scale to specify intensities. This scale is defined as follows:
If the intensity of sound in watts per square metre is I, then the intensity level in decibel (dB) is given by
dB= 10 log(I/I•),
Where the base of logarithm is 10,
I•=10^-12 watt per square metre( roughly the intensity at which audible sound can be heard)
On the decibel scale the pain threshold is 1 watt per square metre and on decibel scale is:
dB= 10 log(1 watt per square metre/10^-12 watt per square metre)
dB= 10 log ( 1/10^-12)= 10* log (10^12)=10*12=120 dB
In the given problem
dB= 10 log ( 20 I/I)= 10* log 20=10*1.3010=13dB